Adjustable chair or stool



J. BRIGGS. ADJUSTABLE'GHAIR 0R STOOL.

(No Model.)

910. 428,664 Patented May 27, 1890.

' UNITED STATES PATENT OFFICE.

JOSHUA BRIGGS, OF BOSTON, MASSACHUSETTS.

ADJUSTABLE CHAIR OR STOOL.

SPECIFICATION forming part of Letters Patent No. 428,664, dated May 27,1890.

Application filed November 25, 1889. Serial No. 331,438- (No model.)

To all whom it may concern:

Be it known that I, JOSHUA BRIGGS, of Boston, county of Suffolk, Stateof Massachusetts, have invented an Improvement in Adjustable Chairs orStools, of which the following description, in connection with theaccompanyin g drawings, is a specification, like letters and numerals onthe drawings representing like parts.

This invention has for the object the production of an improvedadjustable chair or stool, more especially adapted as a musicstool.

In my invention the seat has at each end rigid brackets, the saidbrackets being each provided with a carriage adapted to slide upon aninclined track secured to the main body of the chair, and to hold theseat in adjusted position I have combined therewith a paWl-and-ratchetmechanism constituting a locking device, the pawls being under thecontrol of a rock-shaft exposed at one or both sides of the chair.

Figure l of the drawings in front elevation represents an adjustablechair embodying my invention; Fig. 2, a longitudinal section thereof inthe line at, Fig. 3 being a partial section in the line 93', and Fig. 4is a side View partially broken out.

The chair-frame is composed, essentially, of bifurcated side pieces A,connected by suitable rounds A A the branches of the side pieces beingrepresented as stiffened by a brace B. Each side piece at its innerside, as herein represented, has attached to it a track a, thecross-sectional shape of which is represented in Fig. 3, and below eachtrack is a rack or ratchet plate I), attached by screws 1), the saidrack-plate having a series of notches to be engaged by the pawls c, ofwhich there are two, the said pawls being attached to a rook-shaft 0,supported in suitable bearings in the brackets or arms cl at each sideof the seat 01', which latter is and may be suitably upholstered.

The rock-shaft has a suitable handle, as (1 by which to turn it to causethe pawls to be disengaged from the notches of the rack-plates wheneverit is desired to lower or to raise the seat, the pawls being kept inengagement with the said notches by means of a spring, as 6, shown asattached to the under side of tracks, so as to slide thereon, as bestshown in Figs. 2 and 3.

In the chair herein described the seat is always in horizontal position;but it slides up and down upon inclined tracks.

The brackets 01 are connected together at opposite sides of the seat bymeans of a rung g. r

The round or cross-piece A at the top of the side pieces constitutes aback for the chair, and near this round or cross-piece I have pivoted anauxiliary back D, it being composed'of a wooden bar, the ends of whichare inserted into and secured in sockets or openings formed in two metalarms D, pivoted to the side pieces at D the said pivots being hereinsupposed to be studscrews. This auxiliary back may be either used in thefull-line position to make an extension upwardly of the back of thechair, or may be turned down into its dotted-line position to close thespace between the cross-piece A and the seat, the arms D in theirdownturned position resting against suitable stops h.

Viewing Fig. 4, it will be seen that the edge of the bracket 01 next theframe-A is recessed or chambered to receive a spiral spring m, which atits lower end is attached to a stud 10 of the brackets and at its upperend to a suitable stud 011 the frame, there being such a spring on eachbracket. These springs counterbalance the weight of the seat, so that itmaybe moved up and down with great ease, and may be used to advantagewith any form of locking device or adjusting means for the seat.

I claim- 1. A chair composed, essentially, of the side pieces havinginclined tracks a, rack-plates located below and projecting beyond saidtracks, and a vertically-adj ustable seat having brackets rigidlysecured thereto and provided With inclined faces to rest on the sidepieces, to thereby always maintain the seat horizontal, carriagessecured to the inner side of said brackets to embrace the projectingedges of the tracks, and a rock-shaft having its bearings in saidbrackets, and pawls eonneeted to said rock-shaft to normally engage saidrack-plates, substantially as described.

2. The combination, with the side pieces, the rack-plates connected tothe inner sides of the side pieces, the horizontal seat havingrigidly-attached brackets, a rock-shaft extended through said bracket-shaving pawls attached thereto, and an arm 6', a spring to normallyactuate the roek-shaft,and handles (Z upon the projecting ends of therock-shaft to turn the same, and thereby remove the v pawls from therack-plates without tilting the seat, of carriages secured to the innersides of the brackets and adapted to engage with and slide on the saidbrackets, substantially as described.

JOSHUA BRIGGS.

WVitnesses'.

Geo. W. GREGORY, E. J BENNETT.

